In this recipe, we will learn how to install Nagios Core version 4, an open-source network monitoring system that checks whether hosts and services are working and notifies users when problems occur or services become unavailable. Nagios provides solutions to monitor your complete IT infrastructure and is designed with an architecture that is highly extendable and customizable and goes far beyond simple bash scripts to monitor your services. (Refer to the Monitoring important server infrastructure recipe in Chapter 3, Managing the System.)
To complete this recipe, you will require a working installation of the CentOS 7 operating system with root privileges, a console-based text editor of your choice, and a connection to the Internet in order to facilitate the download of additional packages. Nagios Core 4 is not available in the official sources but from the EPEL repository; make sure to have installed it before (refer to the Using a third...